1. Field of the Invention
The present invention relates to a position detecting device that can be used by a plurality of users at the same time.
2. Description of the Background Art
A conventional optical position detecting device attached to a display includes a transparent input panel disposed over the display screen surface, and optical sensor units disposed at the side of the input panel surface. The optical sensor units are located on both sides near the upper edge of the display device, and they emit and receive scanning light in a parallel plane at a given distance from the input panel. A retro-reflection member is provided around the input panel to retro-reflect the light emitted from the optical sensor units. When a finger or a specialized pen points at a point on the display screen, an image processing means performs analysis with the retro-reflected light received at the optical sensor units, so as to calculate the pointed coordinate position (for example, see Japanese Patent Application Laid-Open No. 2004-5171).
The position detecting device described above is capable of recognizing a single user, but is incapable of recognizing a plurality of users when used by two or more users.